docs: def next(self, data, final = False, to_buffer = False):
          """
          Add more input to the HMAC SHA1.
          """
          if final:
              self.flags = pyhsm.defines.YSM_HMAC_SHA1_FINAL
          else:
              self.flags = 0x0
          if to_buffer:
              self.flags |= pyhsm.defines.YSM_HMAC_SHA1_TO_BUFFER
          self.payload = _raw_pack(self.key_handle, self.flags, data)
          self.final = final
          return self